This type of tubular reaction furnace consists of a building-like steel structure. Walls, ceiling and floor have a refractory lining. The furnace is equipped with a plurality of vertical reaction tubes filled with a catalyst and arranged in several rows. In order to achieve uniform withdrawal of the flue gas, a certain number of parallel flue gas ducts are arranged on the floor and connected to a common header where the gas collects. Then the gas passes a heat exchanger and is discharged into the atmosphere via a flue gas stack. Since the flue gas ducts are arranged in the reaction furnace and heated from all sides, they consist of a self-supporting structure of refactory ceramic material or bricks.
Off-shore fields of natural gas or oil offer the possibility of converting such raw materials into intermediate or final products at the place of the resources, i.e. on floating plant platforms. For this purpose, tubular reaction furnaces for cracking hydrocarbons are mounted on special vessels which are called floating plant platforms. Since such a platform is exposed to considerable internal forces depending on the sea waves, the components must withstand major dynamic forces, especially the flue gas ducts of the furnace, because they consist of heavy ceramic material. The weight of these components can in fact cause a collapse of the structure depending on the angle of inclination from the vertical position.